The present invention relates to apparatus for testing rod-shaped articles of the tobacco processing industry, especially for testing the wrappers and/or other portions of plain or filter cigarettes, cigars or cigarillos while the articles travel along a predetermined path and past a testing station. More particularly, the invention relates to improvements in testing apparatus of the type wherein at least one end of each article to be tested is engaged by an elastic sealing element which serves to admit a testing fluid into or to convey a testing fluid from the respective end of the article.
It is already known to admit the articles to be tested into peripheral flutes of a rotary drum-shaped conveyor which transports the articles past the testing station. The condition of the wrappers of articles can be tested by admitting a stream of testing fluid into one or both ends of an article which travels past the testing station and by ascertaining the drop of pressure (if any), i.e., whether or not the wrapper of the article which moves past the testing station has one or more holes, an open seam, a frayed end or a combination of such defects. At least one end of the wrapper of the article must be sealed from the surrounding atmosphere during testing, and such sealing is achieved by resorting to the aforementioned elastic sealing elements which orbit about the axis of the testing conveyor and have sockets for reception of the adjacent ends of the articles. The sealing elements consist of rubber or an elastomeric synthetic plastic material. Furthermore, the testing conveyor is equipped with means for effecting a movement of the sealing elements into engagement with the respective ends of the articles not later than during travel past the testing station and for thereupon disengaging the articles from the sealing elements preparatory to removal of articles from the testing conveyor. This can be accomplished by moving the sealing elements axially of the articles (i.e., in parallelism with the axis of the testing conveyor) under the action of followers which track one or more stationary cams or by providing mobile cams, e.g., in the form of swash plates or the like.
It is further desirable to test the wrappers of cigarettes or analogous rod-shaped articles in order to ascertain the permeability of their so-called climatic zones, i.e., of zones which are formed with intentionally produced perforations. The perforations serve to admit cool atmospheric air into the column of tobacco smoke, and their number as well as their diameters must be constant from cigarette to cigarette because minor and even minute deviations of the desired rate of inflow of cold air from the actual rate are unacceptable to the makers of smokers' products. Therefore, the testing apparatus must operate with a high degree of accuracy because the flow of any, even minute, quantities of atmospheric air as a result of unsatisfactory sealing action in the course of the testing operation can cause the apparatus to furnish highly distorted readings regarding the quality of tested articles with the result that long series of satisfactory articles are segregated together with defective articles or that large numbers of defective articles remain undetected.
Elastic sealing elements which are used for the above outlined purposes are disclosed, for example, in commonly owned U.S. Pat. No. 3,386,281 granted June 6, 1968 to Menge et al. and in commonly owned U.S. Pat. No. 3,769,832 granted Nov. 6, 1973 to Baier. Testing apparatus which serve to ascertain the permeability of so-called climatic zones in the wrappers of filters in filter cigarettes or the like are disclosed, for example, in commonly owned U.S. Pat. No. 4,177,670 granted Dec. 11, 1979 to Heitmann et al. A further apparatus which is used for the testing of cigarettes or the like and wherein the testing conveyor is constructed in a manner similar to that disclosed in the present application is described in commonly owned U.S. Pat. No. 3,948,084 granted Apr. 6, 1976 to Heitmann et al. The disclosures of the aforementioned patents are incorporated herein by reference. The assignee of the present application owns numerous additional U.S. as well as foreign patents and pending patent applications dealing with the testing of cigarettes, filter rod sections, cigars, cigarillos and/or other rod-shaped articles which constitute or form part of smokers' products.
A drawback of many presently known elastic sealing elements for the end portions of cigarettes or the like is that they must be deformed by pneumatic and/or mechanical means in order to move into satisfactory sealing engagement with the end faces and/or external surfaces of the articles to be tested. The means for effecting deformation of sealing elements into adequate engagement with the articles to be tested contribute to the complexity, bulk and cost of the testing apparatus. Furthermore, such deformation effecting means must be serviced and inspected at frequent intervals and are prone to malfunction so that they are a cause of frequent and protracted down times of the machine (e.g., a filter tipping machine) wherein the testing apparatus is installed.